As a filling and packaging machine for filling and packaging contents made of material in a liquid form, a powdery form or a paste form, as disclosed in Japanese Laid-open Patent publication HEI 1-153410, Japanese Laid-open Patent publication HEI 2-4626 or Japanese Laid-open Patent publication HEI 2-32929, a machine which folds back a continuously fed film, overlaps both folded back end peripheries of the film and vertically seals such end peripheries by means of a vertical seal mechanism, fills a content in the inside of the vertically sealed film, laterally seals this film by means of lateral seal mechanisms so as to form pouches and cuts the central portions of the laterally sealed portions by means of a cutter mechanism to separate these pouches as single-pack pouches and transfers them or alternatively laterally seals the film by means of lateral seal mechanisms to form pouches and transfers pouches which are connected in a continuous form, and packages these pouches in an accommodating box, is known. One example of such a machine is explained in conjunction with FIG. 5.
In the drawing, numeral 1 indicates a machine base and holder frames 2 are disposed at the side portion of the machine base 1. Film rolls R which is made of films F wound in a roll form are replaceably mounted on the holder frames 2. A film guide portion 3 and a film folding back portion 4 are disposed at the upper portion of the machine base 1. To the front surface portion of the machine base 1, a vertical seal mechanism 5, a first and second lateral seal mechanisms 6, 7, and a cutter mechanism 8 are provided in the order from above. The film F is pulled out from one film roll R in a roll form and the film F is lead out to the film folding back portion 4 by way of the film guide portion 3. The film F is folded back in a double folded manner along a longitudinal direction by the film folding back portion 4. The folded back end peripheral portions of the film F are subjected to a heat seal by means of a pair of vertical seal rolls 9 of the vertical seal mechanism 5 which face each other in an opposed manner and then are fed out. The film F is formed in a cylindrical shape by means of this vertical seal portion FH. The film F is heat sealed in a lateral direction by means of a pair of lateral seal rolls 10 of the first lateral seal mechanism 6 which face each other in an opposed manner so as to form bottoms of packing bags by means of these lateral seal portions FS. In the inside of the film F formed in a cylindrical shape having the bottom, a content W made of a liquid such as sauce is filled. The film F is further advanced and the bag opening side of the film F is again laterally sealed by means of a pair of lateral seal rolls 10 of the first lateral seal mechanism 6 to hermetically fill the content W and this lateral sealed portion FS is again hermetically sealed so as to seal three sides of the film F thus forming pouches P by means of a pair of lateral seal rolls 10A provided to the second lateral seal mechanism 7. Subsequently, the intermediate portions of the lateral sealed portions FS which are provided for forming the pouches P are cut by the cutter mechanism 8 so as to form pouches P in a single-pack form and the pouches are transferred. Alternatively, after forming pouches P by laterally sealing the film F by means of the lateral seal mechanisms 6, 7, the operation of the cutter mechanism 8 is stopped and the pouches P in a continuous-pack form which are made of continuously connected pouches P are transferred.
Furthermore, the above-mentioned pouches P which are formed such that three sides thereof are sealed may be formed as shown in FIG. 6, wherein the pouch P which is filled with the content W is formed by a vertical sealed portion FH which is formed by heat sealing both folded back end portions of the film F by means of the vertical seal rolls 9 and the lateral seal portions FS which are heat sealed by means of the lateral seal rolls 10, 10A in a direction perpendicular to the longitudinal direction of the film F.
Furthermore, as shown in FIG. 7, the pouches P may be formed such that four sides of the film F are sealed by vertical seal portions FH1, FH2 which are formed by respectively heat sealing the folded back end portions and the back-like peripheral portion of the film F by means of two vertical seal rolls not shown in drawings and lateral seal portions FS which are formed by heat sealing the film F by means of lateral seal rolls not shown in drawings in a direction perpendicular to the longitudinal direction of the film F.
Furthermore, as shown in FIG. 8, the pouches P may be formed such that two sheets of films F1, F2 are overlapped and pulled out while being guided, both side peripheral portions of these films F1, F2 are respectively heat sealed by two vertical seal rolls not shown in drawings to form a bag in a cylindrical form with vertical sealed portions FH1, FH2 at both sides of the films F1, F2 and subsequently, lateral sealed portions FS are formed by heat sealing the bag by means of lateral seal rolls not shown in the drawing in a direction perpendicular to the longitudinal direction of the film F so as to form pouches P which have four sides thereof heat sealed.
Furthermore, a filling and packaging machine shown in FIG. 9 or the like is also proposed. In the drawing, a sheet of film F is pulled out while being guided in a half folded condition, the folded back end portions which are half folded back and the central portion of the folded back film F are respectively heat sealed by two vertical seal rolls not shown in the drawing such that cylindrical bags in two rows are formed by the heat sealed vertical seal portions FH1, FH2, and contents W1, W2 of different kinds, sauce and mayonnaise or soy sauce and spicy oil, for example, are filled in cylindrical bags of respective rows, and subsequently, the film F is heat sealed in a direction perpendicular to the longitudinal direction of the film F by means of lateral seal rolls not shown in the drawing, whereby pouches P are packaged and sealed in two rows by these heat sealed lateral sealed portions FS and the above-mentioned vertical sealed portions FH1, FH2.
By the way, at the time of forming the packaging pouches P as shown in the above-mentioned FIG. 7-FIG. 9, in case the width or the vertical seal position of the pouch P to be packaged is different, in general, as shown in FIG. 10, at least one vertical seal roll 9A out of vertical seal rolls 9, 9A which are fixedly mounted on the rotating shaft 5A of the vertical seal mechanism 5 is movably adjusted relative to the rotating shaft 5A corresponding to the width and the vertical seal position of the film F and hence, the vertical sealed position FH2 is set corresponding to the width of the pouch P.
In this case, the rotating shaft 5A is inserted in the vertical seal roll 9A such that the vertical seal roll 9A is disposed around the outer peripheral portion of the rotating shaft 5A. This vertical seal roll 9A is mounted on and fixedly secured to the rotating shaft 5A at a given position by fastening with bolts or the like.
Here, a heater not shown in the drawing is incorporated in the rotary shaft 5A and the heat of this heater is transmitted to the vertical seal rolls 9, 9A by way of the rotating shaft 5A and hence, the vertical seal rolls 9, 9A are heated. The conventional heater, however, is fixedly secured to the rotating shaft 5A and hence, a given temperature distribution is present corresponding to the mounting position of the heater relative to the rotating shaft 5A. In general, in a longitudinal direction of the heater, the temperature takes the highest value around the central portion of the heater and is lowered gradually in a direction from the central portion to the end portions of the heater. In this case, to compare the movable vertical seal roll 9A with the fixed vertical seal roll 9, the distances between the respective vertical seal rolls 9, 9A and the heater are different so that the surface temperatures of the seal portions of the vertical seal rolls 9, 9A become different and hence, the vertical sealed portion FH1 and the vertical sealed portion FH2 differ in the sealed condition.
Accordingly, although the heater can cope with pouches with a narrow distance between the vertical sealed portion FH1 and the vertical sealed portion FH2, this temperature difference becomes remarkable with respect to pouches with a wide distance between the vertical sealed portion FH1 and the vertical sealed portion FH2. Therefore, while the proper sealing is obtained at one vertical sealed portion, the film is excessively fused at the other vertical sealed portion or, in an opposite case, the film is insufficiently fused or adhered thus resulting in the sealing failure.
Furthermore, two pairs of vertical seal rolls 9, 9A differ in their respective shapes and volumes and hence, they differ in the heat capacities, the manner of transmitting heat and also in the heat radiation condition. Although the surface temperatures of the sealed portions of two pairs of the vertical seal rolls 9, 9A may be made equal by performing a calculation in a thermal engineering manner corresponding to the volumes and the shapes and then, by differing the winding densities of the heater in a longitudinal direction of the heater, for example, there arises a problem that it pushes up the design cost and the manufacturing cost.
Accordingly, it is an object of the present invention to provide a heat seal device of a filling and packaging machine which can assure the stable sealed condition of the vertically sealed parts, wherein the surface temperatures of the sealed portions which are respectively provided to two pairs of vertical seal rolls mounted on the rotating shafts with a given distance in an axial direction of the rotating shafts are made substantially equal with a simple construction.